What is the function of saliva?

The saliva fulfils several important functions in the oral cavity. On the one hand, it plays an extremely important role in food intake and digestion. First of all, saliva causes the soluble components of food to dissolve, resulting in a fluid food pulp that is easier to swallow.

In addition, saliva starts the digestion of large carbohydrates in the oral cavity, which have already been broken down into smaller fragments by the enzyme ptyalin (an amylase). In addition, saliva fulfils a task in the defence against pathogenic germs such as bacteria, viruses or fungi. It also contributes to cleaning and disinfecting the oral mucosa. It should also be noted that saliva simply takes over the function of moistening the oral cavity, which may seem unspectacular at first, but is ultimately the reason why we can speak, taste or even smell properly at all. Saliva also makes a not unimportant contribution to the health of our teeth: it protects the tooth substance and controls the formation of plaque, while at the same time ensuring the remineralization of the teeth, since it contains fluoride and rhodanide, substances essential for the enamel.

Stimulation of the salivary flow

The messenger substance norepinephrine causes the much more viscous, mucous-containing saliva is produced. Acetylcholine, on the other hand, causes much watery saliva to be squeezed out of the saliva-producing glands. Depending on the stimulation, 0.1 to 4 ml of saliva is secreted per minute.

Over the course of the day this makes 0.5 to 1.5 liters of saliva. The glandula parotis (parotid gland) produces serous saliva, i.e. watery saliva, and the glandula submandibularis (mandibular salivary gland) produces mucinous saliva, i.e. slimy saliva.

In addition to the autonomic nervous system, other stimuli also have an influence on saliva production. Appealing smells and the taste and food stimulate them (“that’s where your mouth starts to water”). Massaging the salivary glands also causes more saliva to leak out.

If nausea occurs, the production of saliva is increased. If vomiting occurs, the saliva should protect the teeth from stomach acid. Furthermore, the flow of saliva can be stimulated by conditioning alone (classical conditioning according to Pawlow). A conditional stimulus (such as the clattering of plates) is sufficient to achieve the conditional reaction of salivation.